I'd say ditch the DTS track, because although it is better than DD, it will still just be a compressed version of the PCM track. If you put the PCM track on there you are getting the best sound possible from the LDs.
Not all DVD players can play DTS tracks, nor can older amplifiers decode it. But even ancient stereos can decode Pro Logic, and DVD players can all play PCM (they must in order to play music CDs).
So it's a choice of a compressed, less compatible DTS track, or a pure, highly compatible PCM track - I know which one I'd go for!